US4705592A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing printed circuits
Assignee: International Business Machines Corp
•
Filing: 1986-12-18
•
Granted: 1987-11-10
•
Expires: 2006-12-18
Abstract
Abstract A process for producing printed circuits including a dry substrate activation process and copper deposition without electroless plating is disclosed. The process requires fewer wet chemical baths, is less environmentally hazardous, and more efficient than conventional processes. Initially, sacrificial copper layers are laminated to the surface of a prepreg substrate and through holes are drilled therein. The sacrificial layer is then removed by etching and copper is sputter deposited upon the substrate surface and the walls of the through holes. Photoresist is then applied, exposed and developed to create the desired pattern of circuit lines. Next, copper is deposited in the photoresist channels and on the through hole walls by electroplating. After the photoresist is stripped, the exposed sputtered copper is removed by differential etching.
Inventors
- 👤 Dieter Bahrle
- 👤 Friedrich Schwerdt
- 👤 Jurgen H. Stehling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:41
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/38; H05K3/381; H05K3/10; H05K3/108; H05K3/40; H05K3/4038; H05K3/4076; H05K3/42; H05K3/425; H05K3/426; H05K2203/00; H05K2203/11; H05K2203/1152; H05K3/388; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49124; Y10T29/49155; Y10T29/49165
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
75 words
A process for producing printed circuits comprising the steps of: sputtering a conductor onto an insulating substrate surface and the walls of through holes therein; applying a layer of photoresist to the insulating substrate surface; photolithographically creating channels in the photoresist; depositing a conductor in the channels and on the walls of the through holes by electroplating; stripping the photoresist; and differentially etching to remove the sputtered conductor exposed by the stripping of the photoresist.
Claim 2
Dependent Claim
75 words
A process for producing printed circuits comprising the steps of: sputtering a conductor onto an insulating substrate surface and the walls of through holes therein; applying a layer of photoresist to the insulating substrate surface; photolithographically creating channels in the photoresist; depositing a conductor in the channels and on the walls of the through holes by electroplating; stripping the photoresist; and differentially etching to remove the sputtered conductor exposed by the stripping of the photoresist.
Claim 3
Dependent Claim
18 words
The process of claim 1 wherein the steps are simultaneously implemented on both sides of the insulating substrate.
Claim 4
Dependent Claim
107 words
A process for producing printed circuits comprising the steps of: laminating a sacrificial layer to an insulating substrate surface; drilling through holes in the insulating substrate; etching the sacrificial layer off of the insulating substrate surface; sputtering a conductor onto the insulating substrate surface and the walls of the through holes therein; applying a layer of photoresist to the insulating substrate surface; exposing and developing the photoresist to create channels in the photoresist; depositing a conductor in the channels and on the walls of the through holes by electroplating; stripping the photoresist; and differentially etching to remove the sputtered conductor exposed by the stripping of the photoresist.
Claim 5
Dependent Claim
107 words
A process for producing printed circuits comprising the steps of: laminating a sacrificial layer to an insulating substrate surface; drilling through holes in the insulating substrate; etching the sacrificial layer off of the insulating substrate surface; sputtering a conductor onto the insulating substrate surface and the walls of the through holes therein; applying a layer of photoresist to the insulating substrate surface; exposing and developing the photoresist to create channels in the photoresist; depositing a conductor in the channels and on the walls of the through holes by electroplating; stripping the photoresist; and differentially etching to remove the sputtered conductor exposed by the stripping of the photoresist.
Claim 6
Dependent Claim
25 words
The process of claim 3 wherein the steps, except for the drilling of through holes, are simultaneously implemented on both sides of the insulating substrate.
Claim 7
Dependent Claim
105 words
A process for producing printed circuits comprising the steps of: laminating a sacrificial copper layer to the surface of a prepreg substrate; drilling through holes in the substrate; etching the sacrificial layer off of the substrate surface; sputtering copper onto the substrate surface and the walls of the through holes therein; applying a layer of photoresist to the substrate surface; exposing and developing the photoresist to create channels in the photoresist; depositing more copper in the channels and on the walls of the through holes by electroplating; stripping the photoresist; and differentially etching to remove the sputtered copper exposed by the stripping of the photoresist.
Claim 8
Dependent Claim
105 words
A process for producing printed circuits comprising the steps of: laminating a sacrificial copper layer to the surface of a prepreg substrate; drilling through holes in the substrate; etching the sacrificial layer off of the substrate surface; sputtering copper onto the substrate surface and the walls of the through holes therein; applying a layer of photoresist to the substrate surface; exposing and developing the photoresist to create channels in the photoresist; depositing more copper in the channels and on the walls of the through holes by electroplating; stripping the photoresist; and differentially etching to remove the sputtered copper exposed by the stripping of the photoresist.
Claim 9
Dependent Claim
24 words
The process of claim 5 wherein the steps, except for the drilling of through holes, are simultaneously implemented on both sides of the substrate.
Claim 10
Dependent Claim
31 words
The process of claim 5 wherein said lamination of the sacrificial layer occurs at approximately 190° C. to produce a layer of copper of approximately 0.0175 to 0.03 mm in thickness.
Claim 11
Dependent Claim
19 words
The process of claim 5 wherein said etch to remove the sacrificial layer occurs in a high-pressure spray system.
Claim 12
Dependent Claim
29 words
The process of claim 5 wherein said sputtering of copper occurs in a magnetron-enhanced high-power cathode sputtering system to produce a layer approximately 80 to 500 nm in thickness.
Claim 13
Dependent Claim
19 words
The process of claim 9 wherein said sputtering of copper produces a layer of approximately 200 nm in thickness.
Claim 14
Dependent Claim
23 words
The process of claim 5 wherein said application of the photoresist occurs by lamination at a temperature of approximately 110° to 120° C.
Claim 15
Dependent Claim
21 words
The process of claim 11 wherein the photoresist is a negative photoresist comprising polyethylene terephthalate, benzophenone, and an acryl acid/styrol polymer.
Claim 16
Dependent Claim
17 words
The process of claim 5 wherein said developing of the photoresist occurs in an aqueous alkaline solution.
Claim 17
Dependent Claim
40 words
The process of claim 5 wherein said deposition of copper by electroplating occurs in a bath containing 15 to 25 g/l Cu 2+ , 170 to 200 g/l H 2 SO 4 , 40 to 60 mg/l Cl - .
Claim 18
Dependent Claim
33 words
The process of claim 14 wherein said deposition of copper by electroplating occurs at a current density of approximately 2.5 A/dm 2 to yield a deposition rate of approximately 25 to 30 microns/h.
Claim 19
Dependent Claim
17 words
The process of claim 5 wherein said stripping of the photoresist occurs in an aqueous alkaline solution.
Claim 20
Dependent Claim
34 words
The process of claim 5 wherein said differential etching of the sputtered copper occurs in a solution containing approximately 100 to 130 g/l sodium peroxodisulphate and approximately 60 to 90 ml/l concentrated sulphuric acid.
References Cited (Backward Citations)
US2982625A
Cited
DE1496984A1
Cited
US3675318A
Cited
DE2135384A1
Cited
DE2515706A1
Cited
GB1588780A
Cited
DE3304004A1
Cited
US4556628A
Cited
US4521280A
Cited
US4581301A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-11-09 | 1991-05-11 | 1991-11-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-09 | 1995-05-11 | 1995-11-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-09 | 1999-05-11 | 1999-11-10 | $7700.00 | Window Closed / Lapsed |